Diane 'Gives' Her All

Diane Keaton is taking it all off in her new movie - more than 25 years after her first nude scene.

And at the age of 57, she's as sexy as ever.

"There was nudity in 'Looking for Mr. Goodbar' in 1977," Keaton says in her familiar patter. "But people forget that, because I guess I'm usually clothed!"

In "Goodbar," Keaton was topless, but in "Something's Gotta Give" - which hits theaters tomorrow - she gives the full Monty to co-star Jack Nicholson and movie audiences.

Keaton sees her skin-ful performance as part of a reciprocal arrangement.

"It's no big deal," she says. "If Jack's running around with his butt hanging out in a hospital gown, then I've got to be this naked fiftysomething woman, you know? Jack makes a fool out of himself, why shouldn't I?

"It's an important aspect of this movie - the idea of intimacy. You have to be willing to give something. It was a required part of accepting the role, and I never for a moment thought I wouldn't do the nudity.

"Mercifully, the lovemaking scenes were clothed!"

In "Something's Gotta Give," Keaton is so desirable she's wooed by two very different men: Nicholson, 66, and 39-year-old Keanu Reeves.

She says that getting steamy with Reeves was, well, odd.

"It was pretty embarrassing, and for Keanu, too," Keaton says. "It has to do with time of life. It's instinctive - [while kissing him] you go, 'Uh, probably not!'

"And Keanu was going, 'Definitely not!' He was trying to be polite. But he's so beautiful, it's stupefying. It was a guilty pleasure. A very guilty pleasure."

The Academy Award winner - for "Annie Hall" in 1977 - and multiple nominee - for "Reds" (1981) and "Marvin's Room" (1996) - just snagged a National Board of Review award for "Something's Gotta Give," fueling buzz of yet more Oscar gold.

Her continued success comes as no surprise to frequent screen partner and ex-love Woody Allen.

"Diane has gone her own route over the decades, and has proved to be a ­perennial, beyond fashion or trends," Allen told the Daily News.

"She proves that the cream rises to the top and stays there."

Keaton's vocal rhythms are still punctuated by giggles and endearing utterances like "Oh, wow, yeah." In her brown men's wear hat and tweed coat - but sans gloves, her favorite fashion accessory - she's as cute as ever.

And she's taking the renewed interest in her with a sense of humor.

"I feel like Seabiscuit. The ol' gal. In her final race, she's too old, but still she does it. Then they retire her," she smiles.

"Are they gonna retire me? Don't retire me yet! Give me one more!"

Keaton, who never married (she has two adopted children - 3-year-old son Duke and daughter Dexter, 8), says she likes to stay pals with her exes, ­including Allen, Warren Beatty and Al Pacino.

"In some cases, it's easy to remain friends - I never see Woody enough - and in others it takes more time, because you get hurt, you know?" Keaton says. "But pain is part of it. Falling in love is a scary proposition.

"That's why it's so sweet to play being in love in a movie, because you win. You go in knowing you'll be saved."

Though her real-life romantic history has been with older men, Keaton did have one experience in the other direction - during auditions for her 1983 drama "Mrs. Soffel," co-starring Mel Gibson.

"I was in my upper 30s, and Tom Cruise, Kevin Costner, all these young guys tried out for a role," she recalls.

"The worst was literally touching Tom Cruise. Honest to God, his chest was like a rock, like a tree trunk - there was no softness.

"Tom was bouncy, like a springer spaniel. Keanu is, too. Keanu would leap all over me. I was like, 'Whoa, go a little slower, babe!' He was like a Jack-in-the-box."

Her scenes with Nicholson were different: They compared past romances as they lolled in bed waiting for the cameras to roll.

"Failed romances," Keaton corrects. "I started right in, since I knew the way to Jack was to just be direct and say, 'Okay, did you have an affair with so-and-so?'"

Keaton laughs at reports that she and Nicholson - who usually dates much younger women - have become an item since filming the movie.

"Concerning Jack, the rumors are hilarious, and I'm honored that anyone would consider me Jack-worthy," she says.

"When I was with Warren, I got to know Jack slightly. Then when we made 'Reds' [in which Nicholson co-starred], I got to know him better, if briefly.

"We never dated, never did. I think we both probably thought, 'Why didn't we?' But it wasn't fated to happen. It's all timing."